Electrical connector plug and connector assembly



Dec. 22, 1970 M CALLER ET AL 3,550,064

ELECTRICAL CONNECTOR PLUG AND CONNECTOR ASSEMBLY Filed Aug. 6, 1969 Pau/J. Kann/'ck BY v Allorney United States Patent O 3,550,064 ELECTRICALCONNECTOR PLUG AND CONNECTOR ASSEMBLY James M. Caller and Paul J.Konnick, Albuquerque,

N. Mex., assignors to the United States of America as represented by theUnited States Atomic Energy Commission Filed Aug. 6, 1969, Ser. No.847,870 Int. Cl. H01r 13/ 62 U.S. Cl. 339-65 10 Claims ABSTRACT 0F THEDISCLOSURE An ultraminiaturized, high-voltage coaxial cable connectorincluding a connector plug assembly having long electrical dischargepaths from its socket formed from an elongated projecting insulativemember, heat shrunk insulative sleeve, and an insulative sealantinjected into a chamber formed by the insulative member, insulativesleeve, cable insulator and plug housing to effectively form a unitaryinsulative structure within and projecting from the housing. Theinsulative member, insulative sleeve and cable insulator have roughenedand/or primed surfaces facing the chamber for adhesive gripping by theinsulative sealant. A connector receptacle assembly for mating with theplug assembly includes an elongated insulative receptacle member forreceiving the projecting socket insulative structure and a contact pinto engage the plug assembly socket, the insulative receptacle memberhaving extended external and internal electrical creepa'ge paths to itshousing.

BACKGROUND OF INVENTION Present space, aero space and relatedtechnologies are increasingly requiring the development ofultraminiaturized electronic equipment and parts with consequentlyincreased electrical strains or withstand (holdoff) strengths per unitsize or dimension. One area where such requirements of minimum size withmaximum withstand are particularly diflcult to obtain is in electricalconnectors and connector components. It is desirable that electricalconnectors, such as for coaxial cables, have a high-voltage withstandstrength between connector pin and metal housing, possibly for thousandsof volts, in a connector having a very small overall size, such as aboutl to 1.5 inches long.

These demands may be particulary difficult to meet with connectors whichmay be used at high altitude; e.g. altitudes including those above30,000 feet. In accordance with the well known relationship commonlyreferred to as Paschens Law or Curve, the breakdown potential betweenpoints at different potentials in air decreases almost linearly asaltitude increases to about 140,000 to 160,000 feet and then increasesat a relatively rapid rate as altitude continues to increase. Forexample, between about 30,000 feet and 160,000 feet, the breakdownvoltage may decrease about 95% or more (from sea level about 97.5% themost rapid decrease occurring between about sea level and 50,000 feet.Thus, an ultraminiaturized highvoltage connector designed to operate andwithstand 5,000 volts at sea level, may breakdown at about 300 volts orless at 160,000 feet. A microminiaturized connector which may withstandhigh voltages at relatively low altitudes and which may be used orreadily modified to withstand the same voltage at high altitudes maytherefore be particularly desirable.

SUMMARY OF INVENTION It is therefore an object of this invention toprovide a novel ultraminiaturized electrical connector and connector3,550,064 Patented Dec. 22, 1970 ICC components having high voltagewithstand capabilities.

It is a further object of this invention to provide an ultraminiaturizedelectrical connector and connector components which are capable ofmaintaining its highvoltage withstand capabilities at high altitudes.

Various other objects and advantages will appear from the followingdescription of one embodiment of the invention, and the most novelfeatures will be particularly pointed out hereinafter in connection withthe appended claims.

The invention comprises a plug assembly having an elongated projectinginsulative member, heat-shrunk insulative sleeve, and insulative sealantinjected into a chamber formed by these insulative parts and the plugassembly housing surrounding a coaxial cable and conductive socket, theinsulative member, sleeve and cable insulator having roughened and/orprimed surfaces facing the chamber for adhesively gripping the sealant,said plug assembly being mateable with a connector receptacle assemblyhaving an elongated hollow insulative member, and a contact pin toengage the plug assembly contact socket, the hollow insulative memberhaving extended external and internal electrical creepage paths.

DESCRIPTION OF DRAWING The invention is illustrated in the accompanyingdrawing wherein:

FIG. 1 is a cross-sectional plan view of one form of an electricalconnector and connector plug incorporating features of this invention;

FIG. 2 is a fragmentary cross-sectional view of a portion of theconnector plug shown in FIG. l; and

FIG. 3 is a segmented cross-sectional view of a modied embodiment of theconnector of FIG. 1.

DETAILED DESCRIPTION With reference to the embodiment illustrated inFIG. 1, the connector, generally indicated at 10, comprises a receptacleassembly or portion 12 which may be attached by mounting nut 14 and ange16 to a panel 17 or the like for electrical feedthrough and a plugassembly or portion 18 which may be adapted to engage and be fastened toreceptacle portion 12 by a coupling nut 20. Plug portion 18 may befastened to the end of an appropriate coaxial cable 21, as described indetailed below.

Receptacle portion 12 may include an annular housing or shell 22carrying flange 16 and suitably threaded to provide the desiredengagement with mounting nut 14 and coupling nut 20. An elongatedinsulative receptacle member 24 may be mounted within and secured byshell 22 by appropriate flange and groove arrangement 26. Receptaclemember 24 may be suitably molded or otherwise formed with a centrallydisposed bore having a first substantial portion 28 at a diameteradapted to matingly receive a coacting part of plug portion 18 and asecond or remaining portion 30 supporting a contact or connector pin 32.Connector pin 32 may be gripped by bore portion 30 with one endprojecting into bore portion 28 and the other end adapted to beconnected by any suitable means to a source or user of electricalenergy. The exterior surface of receptacle member 24 may be providedwith grooves or irregularities in its outer surface as shown, toincrease the external electrical creepage path between connector pin 32and shell 22.

Plug portion 18 may include a socket member 40 having an expandableopening 42 at one end to receive connector pin 32 and a portion 44 atthe other end adapted to be fastened or connected to the centralconductor 46 of coaxial cable 21. Portion 44 may be formed of a diametercorresponding with or about the diameter of cable central insulator 48terminating with an outwardly disposed fiange or lip 50 intermediateportions 44 and opening 42. Central conductor 46 may be welded,soldered, or otherwise attached to portion 44. A heat-shrinkableinsulative sleeve 52 having an initial diameter loosely fitting about anouter seating periphery of portion 44 and insulator 48 may be heattreated to provide a shrink t and seal between the outer peripheries ofportion 44 and insulator 48 and any gap therebetween and increasedmechanical support. The amount of shrinkage and sealing pressure may bedetermined by the materials used and the temperature of heat treatment.Suitable heat shrinkable materials may be irradiated polyolen,polyvinylidene uoride, or the like. An elongated insulative plug member54, suitably molded or otherwise formed, may be disposed about and incontiguous and gripping relationship with the outer exposed periphery ofsocket member 40 and its flange 50. Plug member 54 may extend in onedirection beyond opening 42 of socket member 40 and include an inwardlyextending guide lip 56 for connector pin 32, and projecting in the otherdirection a sufficient distance to be encompassed by the rst portion 28of receptacle member 24 and beyond, overlying entirely sleeve 52 and aportion of the exposed cable insulator 48. Plug member 54 is preferablyspaced from sleeve 52 and cable insulator 48 some prescribed distancefor purpose to be explained below. The portion of plug member 54extending beyond receptacle member 24 may be threadedly engaged orotherwise fastened to a hollow, tubular extension 58 of a housing meansor shell 60.

Besides tubular extension 58, shell 60 may include a portion 62 rigidlyattached to or forming a part of tubular extension 58, which portion maybe closely tting about cable insulator 48 at a location removed fromsleeve 52 and plug member 54. Portion 62, tubular extension 58, plugmember 54, sleeve 52, and cable insulator 48 cooperate to form a cavityor chamber 64 therebetween having spaced apart ports 66 and 68, such asthrough tubular extension 58, communicating therewith. A suitableinsulative sealant material 70 such as certain silicones like roomtemperaturative vulcanizing castable silicone rubber, may be injectedwithin chamber 64 through ports 66 and 68 to completely fill the entirechamber and provide an adhesive seal to each of the insulative membersor sleeves bordering the chamber. To insure an adhesive seal, theexposed surfaces of plug member 54, sleeve 52, and cable insulator 48facing chamber 64 are preferably suitably prepared including exteriorand interior surfaces of member 54. This preparation may include aroughening of the surfaces such as by Sandblasting or etching, and forhigh-altitude use, the preparation preferably in addition includespriming of all or a substantial portion of all surfaces with aninterface material which bonds to the insulative members or sleeve orcable insulator and with sealant material 70. Such an interface materialis shown with exaggerated thickness in the fragmentary view shown inFIG. 2 as material 72 and may include certain silicone primers oradhesion promoters for the silicone adhesive. The surfaces of member 54covered by material 72 is shown with exaggerated roughness. Interfacematerial 72 may provide a homogeneous bond between parts and anair-tight pressure seal within plug member 54.

Sealant material 70 may be injected into ports 66 and 68 by any suitablepressure injection means such as by use of a hypodermic syringe. Thesealant may be injected into one port while blocking the other portuntil resistance to flow is evident. Then the other port may beunblocked with continued injection of sealant material 70 to flushentrapped air from the chamber 64 and insure a complete chamber fill andthe sealant material then cured.

Additional withstand strength at high altitudes is achieved with anannular, deformable gasket 73 disposed between the end of plug member 54and the end of bore 28 of receptacle member 24. Gasket 73 may be made ofany low compression set material, such as certain silicones, which maybe pressed against the respective insulative members 24 and 54 andconnector pin 32 to provide a seal therewith.

Shell may also include an end cap or collar member 74 having a skirt 76which may be threadedly attached to portion 62 and tubular extensions S8so as to cover and seal ports 66 and 68. Any excess sealant materialwhich leaked from ports 66 and 68 may be used to effect a seal withcollar 74. Collar 74 may be disposed about the outer periphery ofcoaxial cable 21 with an inwardly extending lip 78 for -wedging andgripping the outer braid 80 and insulation of cable 21 between lip 78and a conical extension 82 of portion 62 of decreasing diameter anddirected opposite to or away from tubular extension 58. Conicalextension 82 may be provided with appropriate annular and longitudinalgrooves 84 and 86 for additional gripping of the cable. Shell 60 may besuitably attached to receptacle portion 12 by a coupling nut 20 securedin position by a retaining ring and groove arrangement.

Shell 60 may be modied optionally as shown in FIG. 3 to insure goodconductivity where welding is required such as when using aluminumconductor cables. In such construction, tubular extension 58 is providedwith one or more radially spaced slots or grooves 88 and 90 forreceiving and holding suitably shaped wire bundles 92 and 94 formed fromcable braid 80. Wire bundles 92 and 94 may be welded or brazed withinannular conductives sleeves 96 and 98 of copper or aluminum ascompatible which in turn may be secured into grooves 88 and 90. Collar74 may be modified to include a pair of longitudinal ports 100 and 102communicating with chamber 64 for lling thereof and complete theenclosure of chamber 64.

Shell 22 and tubular extension 58 may be formed in overlappingrelationship and be provided with appropriately shaped and coactingstuds and grooves or keyways to aid in alignment of the plug andreceptacle and permit selective engagement of two or more connectorsmounted in close proximity.

The various conductive parts of the connector, such as shells 22 and 60,may be made of stainless steel or other suitable conductor, and thesocket member 40 may be made of beryllium copper, both appropriatelyplated such as with gold for good conductivity. Insulative plug member54 and receptacle member 24 may be made of long glass fiber-filleddallyl phthalate or other suitable lled or unfilled insulatingmaterials. Cable insulator 48 for the above noted primer may commonly bemade of a material such as irradiated polyolefin, or the like.

A connector made in accordance with this invention having a maximumoutside diameter of 0.21 inch for shells 60 and 22 and a maximumconnected length between the ends of shell 60 and connector pin 32 of1.3 inches without gasket 73 and insulating material 70, is capable ofwithstanding about 5 kilovolts at Sea level between the center conductorand the conductive shells. The lengths of the shortest creepage path,both internal and external, for such a connector may be about 0.5 inch.With gasket 73, insulating material 70, and primer 72 in place asdescribed, this connector will withstand 10 kilovolts and is capable ofwithstanding 25 kilovolts at altitudes through the critical areaincluding the 30,000 to 220,000 feet range.

This connector thus permits connection of cables at very high voltageswith ultraminiaturization at both low and high altitudes.

It will be understood that various changes in the details, materials,and arrangements of the parts, which have been herein described andillustrated in order to explain the nature of the invention, may be madeby those skilled in the art within the principles and scope of theinvention as expressed in the appended claims.

What is claimed is:

1. A high-voltage connector plug for a coaxial cable having a centralconductor and outer braid separated by an insulator, comprising, aconductive socket member rigidly secured to said cable central conductorhaving an outer seating periphery adjacent said cable, an insulativesleeve overlapping said seating periphery of the socket member andoverlapping an adjacent outer periphery of said cable insulator andhaving a shrink t against both said peripheries, an elongated insulativemember disposed about and gripping said socket member having one endportion projecting beyond said insulative sleeve and spaced from thecable insulator and a portion of said insulative sleeve and another endportion including an inwardly extending connector pin guiding lip, saidprojecting end portion of the elongated insulative member havingroughened exterior and interior surfaces, housing means for supportingsaid insulative member and said cable having a portion about said cableat a location spaced from said insulative member with a tubularextension spaced from said cable insulator forming a chamber thereaboutand threadedly engaged with said insulative member, said housing meansalso having a pair of spaced apart ports therethrough communicating withsaid chamber, and injected insulative sealant lling said chamber andports and the space intermediate said cable insulator, insulative sleeveand insulative member and gripping the roughened interior and exteriorsurfaces of said insulative member.

2. The connector of clairn 1 including an interface material between theouter surfaces of said cable insulator and insulative sleeve and theroughened surfaces of said insulative member Within said chamber foradhesively gripping said insulative sealant.

3. The connector plug of claim 1 wherein said housing means includes acollar member threadedly engaging and overlying a portion of saidtubular extension.

4. The connector plug of claim 3 wherein said housing n means includes aportion closely tting about said cable insulator at said location spacedfrom said insulative member with said ports disposed through saidtubular extension, and said collar member includes a skirt overlying andsealing said ports.

5. The connector plug of claim 4 wherein said closely fitting portion ofsaid housing means includes a conical extension of decreasing dimensiondisposed away from said tubular extension and said collar means includesa lip clamping said cable outer braid against said conical extension.

6r. The connector plug of claim 5 wherein said conical extensionincludes longitudinal and annular grooves for gripping said cable outerbraid.

7. The connector plug of claim 3 wherein said cable outer braid isseparated into a pair of wire bundles and said housing means includes apair of oppositely disposed slots enclosed within said collar member forreceiving and gripping said bundles.

8. The connector plug of claim 7 wherein said ports are disposed in saidcollar member.

9. The connector plug of claim 1 including a mating receptacle portioncomprising an annular shell, an elongated insulative receptacle memberincluding a centrally disposed bore with a substantial portion at adiameter for receiving said plug insulative member, a connector pinprojecting into said substantial portion of said bore gripped by theremaining portion of said bore for mating relationship with said guidinglip and socket member of said connector plug, and an annular sealinggasket disposed about said pin between said mating insulative members.

10. The connector of claim 9 wherein said insulative receptacle memberincludes an extended electrical creepage path along its outer surfacebetween said connector pin and said annular shell.

References Cited UNITED STATES PATENTS 3,292,136 12/1966 Somerset339--177 3,336,563 8/1967 Hyslop 339--61 3,492,408 l/l970 Forney, Jr.,et al 174-75 MARVIN A. CHAMPION, Primary Examiner I. H. MCGLYNN,Assistant Examiner U.S. Cl. XR. 339-94, 177, 275

